A load signal acquisition device for a shock absorber assembly

Abstract

The invention relates to a shock absorber assembly load signal acquisition device, comprising a shock absorber assembly body, on which mounting hole one, mounting hole two and mounting hole three are distributed, strain gauge mounting groove one and strain gauge mounting groove two are respectively arranged on the left and right sides of mounting hole one, strain gauge mounting groove three and strain gauge mounting groove four are respectively arranged on the left and right sides of mounting hole two, strain gauge mounting groove five and strain gauge mounting groove six are respectively arranged on the left and right sides of mounting hole three, each strain gauge mounting groove is provided with a group of strain gauge sensors, each group of strain gauge sensors is divided into an outer side and an inner side, and each side is divided into positive and negative poles, and the positive and negative poles of six groups of strain gauge sensors are connected in series to form a signal positive pole, a signal negative pole, a power supply positive pole and a power supply negative pole signal collection unit; the invention can obtain objective and accurate load signals, improve the accuracy of virtual design, reduce the number of engineering changes, save development time and cost, and improve vehicle development efficiency.

Description

[Technical field]

[0001] The invention relates to the technical field of vehicle shock absorbers, in particular to a shock absorber assembly load signal acquisition device. [Background Technology]

[0002] Shock absorbers are key components for improving comfort and controlling handling performance in vehicles. In passenger cars and trucks, at least two shock absorbers need to be designed and arranged on each axle to ensure the comfortable operation of the vehicle. At the same time, the arrangement of shock absorbers is also determined by the space and suspension form, and its structural form is also affected by this. At present, the front suspension shock absorber assembly of passenger cars mainly uses a sliding column assembly assembled into an integrated structure of a shock absorber 25, a spring 24, a buffer block 23, a bearing 22, and an upper support assembly 21, as shown in the attached figure. Figure 1 As shown. Based on this design, in order to improve the accuracy of the simulation results in the virtual design stage, the engineering team will use the form of attaching strain gauges to the shock absorber piston rod and spring separately, and obtain the load signals of the spring and shock absorber piston rod in the test vehicle road spectrum collection, supporting virtual development and improving the quality and accuracy of virtual design. However, since the temperature of the shock absorber and the shock absorber piston rod will rise during driving, especially when driving on bad roads, the temperature of the shock absorber will also rise, affecting the signal accuracy of the strain gauge and reducing the quality of the collected signal. This will lead to a decrease in design accuracy and high engineering change costs in the later stage, and at the same time bring about a waste of development time and affect the project progress; on the other hand, the signal collected after the spring patch is affected by key parameters such as the spring's own stiffness and design height, which will lead to deviations from the design parameters.

[0003] Therefore, it will be of great significance if a new shock absorber assembly signal sensor structure can be designed to protect it from the influence of other factors (temperature, manufacturing errors) to obtain objective and accurate load signals, thereby improving the accuracy of virtual design, saving development time, reducing the number of engineering changes, saving development costs, and improving vehicle development efficiency. [Summary of the invention]

[0004] The purpose of the present invention is to solve the above-mentioned deficiencies and provide a shock absorber assembly load signal acquisition device, which can obtain objective and accurate load signals, improve the accuracy of virtual design, reduce the number of engineering changes, save development time and cost, and improve vehicle development efficiency.

[0005] In order to achieve the above-mentioned purpose, a load signal acquisition device for a shock absorber assembly is designed, including a shock absorber assembly body 1, wherein the shock absorber assembly body 1 is evenly distributed with a mounting hole 1 2, a mounting hole 2 3, and a mounting hole 3 4 along the circumferential direction, and the mounting hole 1 2 is respectively provided with a strain gauge mounting groove 1 5 and a strain gauge mounting groove 2 6 on the left and right sides, and the mounting hole 2 3 is respectively provided with a strain gauge mounting groove 3 7 and a strain gauge mounting groove 4 8 on the left and right sides, and the mounting hole 3 4 is respectively provided with a strain gauge mounting groove 5 9 and a strain gauge mounting groove 6 10 on the left and right sides, and the strain gauge mounting groove 1 5, the strain gauge mounting groove 2 6, the strain gauge mounting groove 3 7, the strain gauge mounting groove 4 8, and the strain gauge mounting groove 5 9 and the strain gauge mounting groove 6 10 on the left and right sides. The strain gauge installation slot five 9 and the strain gauge installation slot six 10 are respectively arranged with a first group of strain gauge sensors, a second group of strain gauge sensors, a third group of strain gauge sensors, a fourth group of strain gauge sensors, a fifth group of strain gauge sensors, and a sixth group of strain gauge sensors. The position of each group of strain gauge sensors is divided into an outer side and an inner side, and each side is divided into positive and negative poles. The first group of strain gauge sensors is divided into a positive pole 11a on the outer side of the first group of strain gauge sensors, a negative pole 11b on the outer side of the first group of strain gauge sensors, a positive pole 11c on the inner side of the first group of strain gauge sensors, and a negative pole 11d on the inner side of the first group of strain gauge sensors. The second group of strain gauge sensors is divided into a positive pole 11a on the outer side of the second group of strain gauge sensors, a negative pole 11b on the outer side of the first group of strain gauge sensors, a positive pole 11c on the inner side of the first group of strain gauge sensors, and a negative pole 11d on the inner side of the first group of strain gauge sensors. The third group of strain gauge sensors is divided into a third group of positive electrodes 13a, a third group of negative electrodes 13b, a third group of positive electrodes 13c, and a third group of negative electrodes 13d. The fourth group of strain gauge sensors is divided into a fourth group of positive electrodes 14a, a fourth group of negative electrodes 14b, a fourth group of positive electrodes 14c, and a fourth group of negative electrodes 14d. 4d, the fifth group of strain gauge sensors is divided into the fifth group of strain gauge sensor outer positive electrode 15a, the fifth group of strain gauge sensor outer negative electrode 15b, the fifth group of strain gauge sensor inner positive electrode 15c, and the fifth group of strain gauge sensor inner negative electrode 15d, the sixth group of strain gauge sensors is divided into the sixth group of strain gauge sensor outer positive electrode 16a, the sixth group of strain gauge sensor outer negative electrode 16b, the sixth group of strain gauge sensor inner positive electrode 16c, and the sixth group of strain gauge sensor inner negative electrode 16d, and the positive and negative electrodes of the six groups of strain gauge sensors are connected in series to form a signal positive electrode, a signal negative electrode, a power supply positive electrode, and a power supply negative electrode. Signal collection unit.

[0006] Further, the outer positive electrode 11a of the first group of strain gauge sensors, the outer positive electrode 12a of the second group of strain gauge sensors, the outer positive electrode 13a of the third group of strain gauge sensors, the outer positive electrode 14a of the fourth group of strain gauge sensors, the outer positive electrode 15a of the fifth group of strain gauge sensors, and the outer positive electrode 16a of the sixth group of strain gauge sensors are connected in series in sequence; the outer negative electrode 11b of the first group of strain gauge sensors, the outer negative electrode 12b of the second group of strain gauge sensors, the outer negative electrode 13b of the third group of strain gauge sensors, the outer negative electrode 14b of the fourth group of strain gauge sensors, the outer negative electrode 15b of the fifth group of strain gauge sensors, and the outer negative electrode 16b of the sixth group of strain gauge sensors are connected in series in sequence; the inner positive electrode 11c of the first group of strain gauge sensors, the inner positive electrode 12c of the second group of strain gauge sensors, the inner positive electrode 13c of the third group of strain gauge sensors, the inner positive electrode 14c of the fourth group of strain gauge sensors, the inner positive electrode 15c of the fifth group of strain gauge sensors, and the inner positive electrode 16b of the sixth group of strain gauge sensors are connected in series in sequence. 6c are connected in series in sequence, the inner negative electrode 11d of the first group of strain gauge sensors, the inner negative electrode 12d of the second group of strain gauge sensors, the inner negative electrode 13d of the third group of strain gauge sensors, the inner negative electrode 14d of the fourth group of strain gauge sensors, the inner negative electrode 15d of the fifth group of strain gauge sensors, and the inner negative electrode 16d of the sixth group of strain gauge sensors are connected in series in sequence, the outer positive electrode 11a of the first group of strain gauge sensors is connected in series with the outer negative electrode 11b of the first group of strain gauge sensors, and the signal positive electrode is connected therebetween, the inner positive electrode 16c of the sixth group of strain gauge sensors is connected in series with the inner negative electrode 16d of the sixth group of strain gauge sensors, and the signal negative electrode is connected therebetween, the outer negative electrode 16b of the sixth group of strain gauge sensors is connected in series with the inner positive electrode 11c of the first group of strain gauge sensors, and the power supply positive electrode is connected therebetween, and the outer positive electrode 16a of the sixth group of strain gauge sensors is connected in series with the inner negative electrode 11d of the first group of strain gauge sensors, and the power supply negative electrode is connected therebetween, and the so-called positive and negative electrodes are the principal stress and auxiliary stress directions of the strain gauge.

[0007] Compared with the prior art, the present invention uses a new sensor arrangement method and wiring method, which will not change or damage the original design structure, is not affected by temperature, and has improved accuracy. At the same time, it is more convenient for subsequent virtual design verification. On the other hand, due to the manufacturing error of the spring itself, the load distribution and stiffness distribution fluctuate, and the shock absorber assembly load signal sensor of the present invention is not affected by the spring's own error, but is only related to the actual force, which improves the work efficiency in the process of road spectrum collection and debugging equipment, and also improves the signal quality. In summary, the present invention designs a new shock absorber assembly signal sensor structure to protect it from the influence of other factors (temperature, manufacturing errors) to obtain objective and accurate load signals, so as to improve the accuracy of virtual design, save development time, reduce the number of engineering changes, save development costs, and improve vehicle development efficiency, which is worthy of promotion and application. [Drawings]

[0008] Figure 1 It is a schematic diagram of the structure of the existing shock absorber assembly;

[0009] Figure 2 It is a schematic diagram of the arrangement position and quantity of the strain gauge sensors of the present invention;

[0010] Figure 3 It is a detailed schematic diagram of the location of a strain gauge sensor at one location (six locations in total) of the present invention;

[0011] Figure 4 It is a schematic diagram of the positive and negative polarity details and angle requirements of a certain outer patch of the present invention;

[0012] Figure 5 It is a winding connection relationship diagram of all strain gauge sensor patches of the present invention after completion;

[0013] Figure 6 This is the winding connection relationship of all strain gauge sensor patches of the present invention after completion. Figure 2 ;

[0014] Figure 7 It is a schematic diagram of the load-strain calibration of the assembly after all strain gauge sensor patches of the present invention are connected;

[0015] In the figure: 1, shock absorber assembly 2, mounting hole 1 3, mounting hole 2 4, mounting hole 3 5, strain gauge mounting slot 1 6, strain gauge mounting slot 2 7, strain gauge mounting slot 3 8, strain gauge mounting slot 4 9, strain gauge mounting slot 5 10, strain gauge mounting slot 6 11a, first group of strain gauge sensor outer positive electrode 11b, first group of strain gauge sensor outer negative electrode 11c, first group of strain gauge sensor inner positive electrode 11d, first group of strain gauge sensor inner negative electrode 12a, second group of strain gauge sensor outer positive electrode 12b, second group of strain gauge sensor outer negative electrode 12c, second group of strain gauge sensor inner positive electrode 12d, second group of strain gauge sensor inner negative electrode 13a, third group of strain gauge sensor outer positive electrode 13b, third group of strain gauge sensor outer negative electrode 13c, third group The positive electrode 13d on the inner side of the strain gauge sensor, the negative electrode 14a on the inner side of the third group of strain gauge sensors, the positive electrode 14b on the outer side of the fourth group of strain gauge sensors, the negative electrode 14c on the outer side of the fourth group of strain gauge sensors, the positive electrode 14d on the inner side of the fourth group of strain gauge sensors, the negative electrode 15a on the inner side of the fourth group of strain gauge sensors, the positive electrode 15b on the outer side of the fifth group of strain gauge sensors, the negative electrode 15c on the outer side of the fifth group of strain gauge sensors, the positive electrode 15d on the inner side of the fifth group of strain gauge sensors, the negative electrode 16a on the inner side of the fifth group of strain gauge sensors, the positive electrode 16b on the outer side of the sixth group of strain gauge sensors, the negative electrode 16c on the outer side of the sixth group of strain gauge sensors, the positive electrode 16d on the inner side of the sixth group of strain gauge sensors, the negative electrode 21 on the inner side of the sixth group of strain gauge sensors, the upper support assembly 22, the bearing 23, the buffer block 24, the spring 25, and the shock absorber. [Specific implementation method]

[0016] The present invention is further described below in conjunction with the accompanying drawings:

[0017] The present invention provides a load signal acquisition device for a shock absorber assembly, comprising a shock absorber assembly body 1, wherein the shock absorber assembly body 1 is uniformly distributed with mounting holes 1 2, mounting holes 2 3, and mounting holes 3 4 along the circumferential direction, wherein the mounting hole 1 2 is provided with strain gauge mounting grooves 1 5 and 2 6 on the left and right sides thereof, the mounting hole 2 3 is provided with strain gauge mounting grooves 3 7 and 4 8 on the left and right sides thereof, the mounting hole 3 4 is provided with strain gauge mounting grooves 5 9 and 6 10 on the left and right sides thereof, the strain gauge mounting grooves 1 5, 2 6, 3 7, 4 8, 5 9, The first group of strain gauge sensors, the second group of strain gauge sensors, the third group of strain gauge sensors, the fourth group of strain gauge sensors, the fifth group of strain gauge sensors, and the sixth group of strain gauge sensors are arranged at the strain gauge installation groove 610 respectively. The position of each group of strain gauge sensors is divided into the outer side and the inner side, and each side is divided into positive and negative poles. The first group of strain gauge sensors is divided into the outer positive pole 11a of the first group of strain gauge sensors, the outer negative pole 11b of the first group of strain gauge sensors, the inner positive pole 11c of the first group of strain gauge sensors, and the inner negative pole 11d of the first group of strain gauge sensors. The second group of strain gauge sensors is divided into the outer positive pole 12a of the second group of strain gauge sensors, The second group of strain gauge sensors includes an outer negative electrode 12b, an inner positive electrode 12c, and an inner negative electrode 12d of the second group of strain gauge sensors; the third group of strain gauge sensors includes an outer positive electrode 13a, an outer negative electrode 13b, an inner positive electrode 13c, and an inner negative electrode 13d of the third group of strain gauge sensors; the fourth group of strain gauge sensors includes an outer positive electrode 14a, an outer negative electrode 14b, an inner positive electrode 14c, and an inner negative electrode 14d of the fourth group of strain gauge sensors; The fifth group of strain gauge sensors is divided into an outer positive electrode 15a of the fifth group of strain gauge sensors, an outer negative electrode 15b of the fifth group of strain gauge sensors, an inner positive electrode 15c of the fifth group of strain gauge sensors, and an inner negative electrode 15d of the fifth group of strain gauge sensors. The sixth group of strain gauge sensors is divided into an outer positive electrode 16a of the sixth group of strain gauge sensors, an outer negative electrode 16b of the sixth group of strain gauge sensors, an inner positive electrode 16c of the sixth group of strain gauge sensors, and an inner negative electrode 16d of the sixth group of strain gauge sensors. The positive and negative electrodes of the six groups of strain gauge sensors are connected in series to form a signal collection unit including a signal positive electrode, a signal negative electrode, a power supply positive electrode, and a power supply negative electrode.

[0018] Among them, the outer positive electrode 11a of the first group of strain gauge sensors, the outer positive electrode 12a of the second group of strain gauge sensors, the outer positive electrode 13a of the third group of strain gauge sensors, the outer positive electrode 14a of the fourth group of strain gauge sensors, the outer positive electrode 15a of the fifth group of strain gauge sensors, and the outer positive electrode 16a of the sixth group of strain gauge sensors are connected in series in sequence; the outer negative electrode 11b of the first group of strain gauge sensors, the outer negative electrode 12b of the second group of strain gauge sensors, the outer negative electrode 13b of the third group of strain gauge sensors, the outer negative electrode 14b of the fourth group of strain gauge sensors, the outer negative electrode 15b of the fifth group of strain gauge sensors, and the outer negative electrode 16b of the sixth group of strain gauge sensors are connected in series in sequence; the inner positive electrode 11c of the first group of strain gauge sensors, the inner positive electrode 12c of the second group of strain gauge sensors, the inner positive electrode 13c of the third group of strain gauge sensors, the inner positive electrode 14c of the fourth group of strain gauge sensors, the inner positive electrode 15c of the fifth group of strain gauge sensors, and the inner positive electrode 16b of the sixth group of strain gauge sensors are connected in series in sequence; 16c are connected in series in sequence, the inner negative electrode 11d of the first group of strain gauge sensors, the inner negative electrode 12d of the second group of strain gauge sensors, the inner negative electrode 13d of the third group of strain gauge sensors, the inner negative electrode 14d of the fourth group of strain gauge sensors, the inner negative electrode 15d of the fifth group of strain gauge sensors, and the inner negative electrode 16d of the sixth group of strain gauge sensors are connected in series in sequence, the outer positive electrode 11a of the first group of strain gauge sensors is connected in series with the outer negative electrode 11b of the first group of strain gauge sensors, and the signal positive electrode is connected therebetween, the inner positive electrode 16c of the sixth group of strain gauge sensors is connected in series with the inner negative electrode 16d of the sixth group of strain gauge sensors, and the signal negative electrode is connected therebetween, the outer negative electrode 16b of the sixth group of strain gauge sensors is connected in series with the inner positive electrode 11c of the first group of strain gauge sensors, and the positive electrode of the power supply is connected therebetween, and the outer positive electrode 16a of the sixth group of strain gauge sensors is connected in series with the inner negative electrode 11d of the first group of strain gauge sensors, and the power negative electrode is connected therebetween. The so-called positive and negative electrodes are the principal stress and auxiliary stress directions of the strain gauge.

[0019] The shock absorber assembly load signal acquisition device of the present invention is made of tool steel to replace the shock absorber cover used in the original vehicle. The position of its mounting holes is guaranteed to be consistent with the design. Only the structural shape is changed to arrange and install the six sets of strain signal sensors to be used in the present invention (such as the attached Figure 2 As shown), the positions of the six sets of strain gauges are Figure 2 In: strain gauge installation slot 1 5, strain gauge installation slot 2 6, strain gauge installation slot 3 7, strain gauge installation slot 4 8, strain gauge installation slot 5 9, strain gauge installation slot 6 10. The position of each set of strain gauges is divided into outer and inner sides (as shown in the attached figure). Figure 3 ), and each side has positive and negative poles (as shown in the attached Figure 4 As shown), and the directions of the positive and negative electrodes are clearly required. Figures 2 to 4 After arranging the six sets of sensors, you need to use Figure 5 and Figure 6The wiring method shown connects the positive and negative electrodes of six groups of sensors in series to form a signal collection unit, forming one positive signal, one negative signal, one positive power supply, and one negative power supply. Figure 7 The method shown is used to calibrate the load-strain signal.

[0020] The present invention is carefully designed and can be used in a shock absorber assembly with the same upper support assembly but matched with different shock absorber damping forces and springs after completing patching, wiring, and calibration as required, because its calibration result is not affected by the spring shock absorber and is only related to the magnitude of the force applied to the assembly, which is not achievable in existing design schemes. At the same time, its accuracy is not affected by temperature and the characteristics of the spring itself, and the collected results are highly accurate and true.

[0021] The present invention is not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A shock absorber assembly load signal acquisition device, comprising a shock absorber assembly body (1), wherein the shock absorber assembly body (1) is evenly distributed with a first mounting hole (2), a second mounting hole (3), and a third mounting hole (4) along the circumferential direction, characterized in that: The left and right sides of the mounting hole 1 (2) are respectively provided with a strain gauge mounting groove 1 (5) and a strain gauge mounting groove 2 (6); the left and right sides of the mounting hole 2 (3) are respectively provided with a strain gauge mounting groove 3 (7) and a strain gauge mounting groove 4 (8); the left and right sides of the mounting hole 3 (4) are respectively provided with a strain gauge mounting groove 5 (9) and a strain gauge mounting groove 6 (10); the strain gauge mounting groove 1 (5), the strain gauge mounting groove 2 (6), the strain gauge mounting groove 3 (7), the strain gauge mounting groove 4 (8), the strain gauge mounting groove 5 (9) and the strain gauge mounting groove 6 (10) are respectively arranged with a first group of strain gauge sensors, a second group of strain gauge sensors, ... The third group of strain gauge sensors, the fourth group of strain gauge sensors, the fifth group of strain gauge sensors, and the sixth group of strain gauge sensors are arranged such that the positions of each group of strain gauge sensors are divided into the outer side and the inner side, and each side is divided into positive and negative poles. The first group of strain gauge sensors is divided into the outer positive pole (11a) of the first group of strain gauge sensors, the outer negative pole (11b) of the first group of strain gauge sensors, the inner positive pole (11c) of the first group of strain gauge sensors, and the inner negative pole (11d) of the first group of strain gauge sensors. The second group of strain gauge sensors is divided into the outer positive pole (12a) of the second group of strain gauge sensors, the outer negative pole (12b) of the second group of strain gauge sensors, and the inner positive pole (12d) of the second group of strain gauge sensors. The third group of strain gauge sensors is divided into the third group of strain gauge sensor outer positive electrode (13a), the third group of strain gauge sensor outer negative electrode (13b), the third group of strain gauge sensor inner positive electrode (13c), the third group of strain gauge sensor inner negative electrode (13d), the fourth group of strain gauge sensors is divided into the fourth group of strain gauge sensor outer positive electrode (14a), the fourth group of strain gauge sensor outer negative electrode (14b), the fourth group of strain gauge sensor inner positive electrode (14c), the fourth group of strain gauge sensor inner negative electrode (14d), the fifth group of strain gauge sensors is divided into The fifth group of strain gauge sensors is an outer positive electrode (15a), an outer negative electrode (15b), an inner positive electrode (15c), and an inner negative electrode (15d) of the fifth group of strain gauge sensors. The sixth group of strain gauge sensors is divided into an outer positive electrode (16a), an outer negative electrode (16b), an inner positive electrode (16c), and an inner negative electrode (16d) of the sixth group of strain gauge sensors. The positive and negative electrodes of the six groups of strain gauge sensors are connected in series to form a signal positive electrode, a signal negative electrode, a power supply positive electrode, and a power supply negative electrode.

2. The shock absorber assembly load signal acquisition device according to claim 1, characterized in that: The first group of strain gauge sensor outer positive electrodes (11a), the second group of strain gauge sensor outer positive electrodes (12a), the third group of strain gauge sensor outer positive electrodes (13a), the fourth group of strain gauge sensor outer positive electrodes (14a), the fifth group of strain gauge sensor outer positive electrodes (15a), and the sixth group of strain gauge sensor outer positive electrodes (16a) are sequentially connected in series; the first group of strain gauge sensor outer negative electrodes (11b), the second group of strain gauge sensor outer negative electrodes (12b), the third group of strain gauge sensor outer negative electrodes (13b), the fourth group of strain gauge sensor outer negative electrodes (14b), the fifth group of strain gauge sensor outer negative electrodes (15b), and the sixth group of strain gauge sensor outer negative electrodes (16b) are sequentially connected in series; the first group of strain gauge sensor inner positive electrodes (11c), the second group of strain gauge sensor inner positive electrodes (12c), the third group of strain gauge sensor inner positive electrodes (13c), the fourth group of strain gauge sensor inner positive electrodes (14c), the fifth group of strain gauge sensor inner positive electrodes (15c), and the sixth group of strain gauge sensor inner positive electrodes (16b) are sequentially connected in series; 6c) are sequentially connected in series, the inner negative electrode (11d) of the first group of strain gauge sensors, the inner negative electrode (12d) of the second group of strain gauge sensors, the inner negative electrode (13d) of the third group of strain gauge sensors, the inner negative electrode (14d) of the fourth group of strain gauge sensors, the inner negative electrode (15d) of the fifth group of strain gauge sensors, and the inner negative electrode (16d) of the sixth group of strain gauge sensors are sequentially connected in series, and the outer positive electrode (11a) of the first group of strain gauge sensors is connected in series with the outer negative electrode (11b) of the first group of strain gauge sensors, and a signal is connected between them. The positive electrode (16c) on the inner side of the sixth group of strain gauge sensors is connected in series with the negative electrode (16d) on the inner side of the sixth group of strain gauge sensors and the signal negative electrode is connected therebetween; the negative electrode (16b) on the outer side of the sixth group of strain gauge sensors is connected in series with the positive electrode (11c) on the inner side of the first group of strain gauge sensors and the power supply positive electrode is connected therebetween; the positive electrode (16a) on the outer side of the sixth group of strain gauge sensors is connected in series with the negative electrode (11d) on the inner side of the first group of strain gauge sensors and the power supply negative electrode is connected therebetween; the positive and negative electrodes are the principal stress and auxiliary stress directions of the strain gauges.

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